稀土在激光熔覆涂层中的分布及其对腐蚀性能的能影响

用激光快速熔凝法向金属表层加入稀土，结果表明：激光处理能够把较多的稀土加到钢的表层；钢表层中的过饱和稀土除和氧、硫作用外，还可固溶于晶内、晶界或其附近，甚至能形成金属间化合物ＲＥ２Ｆｅ１７；经过稀土和激光复合处理的表面具有较高的耐腐蚀性能。     

一种激光-稀土复合处理金属表面改性的新方法

提出采用激光熔凝－稀土扩渗复合处理对钢表面改性的新方法。实验结果表明，该方法可以进一步改善渗稀土试样表层显微组织，使其晶粒得到明显细化，组织更加均匀、致密，渗入元素浓度梯度减小，耐腐蚀和抗摩损性能显著提高，可在工业上推广使用。     

40CrNiMoA钢激光淬火+氮化复合处理

对40CrNiMoA钢分别经激光淬火、气体氮化、氮化-激光淬火复合处理及激光淬火-氮化复合处理的硬化层深度及其表面硬度分布进行了比较分析。结果表明，在激光淬火-氮化复合处理中，激光淬火可使随后氮化处理的表层硬度提高100-200HV，硬化层深度可成倍增加；在氮化-激光淬火复合处理中，激光淬火可使预先氮化处理的硬化层深度有大幅度的提高，而表层硬度变化不大。     

稀土渗碳对GCr15钢激光熔凝层摩擦行为的作用

为了提高在航空航天和民用等领域中广泛使用的GCr15钢的表面强度及耐磨性能,采用激光熔凝方法对GCr15钢表面稀土渗碳层进行改性处理,研究了稀土渗碳对激光熔凝改性层摩擦系数及磨损量的影响.结果表明:稀土渗碳使GCr15钢表面激光熔凝改性层的摩擦系数有所下降且在整个摩擦过程中波动较小,磨损失重为未经改性处理的基体材料失重的14%(质量分数);随着摩擦时滑动距离的增加及载荷的加大,稀土渗碳激光熔凝改性处理降低磨损失重的作用也显著增大;稀土渗碳层的磨损形式为犁沟磨损,而稀土渗碳激光熔凝处理的改性层则属于局部擦伤型;稀土渗碳在钢表面激光熔凝处理中的作用主要表现为细化晶粒、微合金化、净化和改善组织致密性.     

稀土元素对38CrMoAl钢氮化层组织和性能的影响

本文研究了在气体氮化渗剂中加入微量稀土元素对38Cr MoAl钢渗层组织和性能的影响。试验结果表明:稀土在氮化时被渗入到钢的表层起了微合金化作用,渗层组织中氮化物的形态、分布和尺寸有明显地改善;稀土氮化处理后的冲击韧性和弯曲疲劳极限较普通氮化处理的有所提高。借助于扫描电镜观察,探讨了氮化层疲劳的机制。     

激光表面重熔对等离子喷涂氧化铝陶瓷涂层耐腐蚀性的影响

通过采用激光表面重熔和在氧化铝涂层中加入稀土的工艺方法，封闭了表层中残存的孔隙，减少了微裂纹。不仅提高涂层的质量，而且使其耐蚀性得到明显提高。     

热浸镀铝层耐人造海水腐蚀性的电化学研究

对Ａ３钢热浸镀铝和铝－稀土的两种镀层在人造海水中的电化学腐蚀行为进行了研究。采用带辅助电极的三电极系统从表层到基体逐层测量了两种动电位曲线;用ＳＥＭ观察并研究了热浸镀层的表面形貌,表层和过渡层的结构。结果表明,在热浸镀铝液中加入稀土,使镀层特别是过渡层明显变薄,且较均匀,表层和过渡层的腐蚀电流都明显减小,因而耐蚀性提高。加入稀土后发现电位逆转现象,有待进一步研究。     

Ce在钢中存在形式及作用的研究进展

Ce是活泼元素。钢液中加入Ce形成含铈硫氧化合物，能够脱氧、脱硫和脱砷，净化钢液，促进钢液凝固形核、细化组织；热力学计算表明CeAlO₃生成自由能最低，生成不同含硫氧化合物与钢液中含氧量、含硫量有关系；微量Ce能固溶于钢中，提高钢的抗腐蚀性能；Ce在钢中也能析出CeFe₂、Fe₄Ce₄C₇或CeC₂等脆性相，降低钢的性能。钢液中形成大量CeAlO₃易聚集堵塞浇注水口，形成Ce₂O₃或Ce₂O₂S分布在基体组织中，使钢在高温轧制时开裂，降低钢的性能。稀土加入低氧钢中能调控碳扩散，优化钢的显微组织和力学性能。     

稀土在钢中应用的新进展

本文概要总结了近年来国内外关于稀土在钢中应用研究的新进展。包括:稀土在钢中的物理化学反应;稀土与钙的比较;稀土加入方法与水口结瘤;稀土在铁中的固溶度限与稀土在钢中的固溶量;稀土在钢晶界上的偏聚及其与其它元素的交互作用;稀土对钢的组织和性能的影响;稀土与钢中氢的反应。     

45钢激光合金化后的组织结构及性能

对45钢激光合金化处理可改善其组织结构及性能。研究了45钢不同工艺条件(功率、扫描速度)下激光处理后的组织结构、成分、显微硬度以及耐腐蚀性能。结果表明:45钢合金化后从表层到基体的区域分为合金化区、过渡区和热影响区,其中合金化区由树枝晶和胞状晶组成;合金化区的显微硬度相对于基体有明显提高,且随扫描速度以及功率的增大,合金化区的硬度增大;45钢合金化后耐腐蚀性能得到了较大的提升。     

Microstructure and mechanical properties of M50NiL steel plasma nitrocarburized with and without rare earths addition

M50NiL steel was plasma nitrocarburized at 500 °C with and without rare earth (RE) addition. The nitrocarburized layers were characterized by optical microscope, scanning electron microscope equipped with an energy dispersive X-ray analyzer, X-ray diffraction, hardness tests and pin-on-disc tribometer. The results show that the RE atoms can diffuse into M50NiL steel surface and change the surface morphology of the nitrocarburized layer. The incorporation of RE atoms increases the surface hardness of the nitrocarburized layer (approximately 130HV_0.1 higher), layer thickness (about 14% thicker) and carbon content of the modified layer, respectively. The wear rates of the nitrocarburized specimens are significantly lower than that of the un-nitrocarburized one. The wear mechanisms of the specimens plasma nitrocarburized with and without RE addition are different mainly due to the differences in the surface morphology, the phase proportion and the hardness of the modified layer.     

Effects of rare earths on nanocrystalline for nitrocarburised layer of stainless steel

Solution-treated stainless steel was plasma-nitrocarburised at the precipitation-sensitive temperature with and without rare earth (RE) addition. The nitrocarburised layers were characterised by means of X-ray diffraction, transmission electron microscope, nanoindentation and anodic polarisation test. Experimental results show that the depth of plasma-nitrocarburised layer can be apparently increased from 60 to 75?μm after RE addition. More importantly, microstructure of stainless steel surface is refined into nano-sized grains after plasma nitrocarburising. At the depth of 20?μm, the hardness and the modulus of the nanocrystallised layer are as high as 13.6 and 218?GPa. After RE addition, the hardness and the modulus of the nanocrystallised layer increase to 17.5 and 255?GPa, respectively.     

稀土对42CrMo钢等离子体氮碳共渗表层组织的影响

对42CrMo钢在不同温度和时间下进行有、无稀土添加的脉冲等离子体氮碳共渗的工艺进行研究。通过金相检验和XRD分析,归纳出稀土对等离子体氮碳共渗的影响。结果表明：稀土的添加改善了渗层的显微组织,并降低了渗氮初期的化合物层厚度;使渗层的e相含量降低,γ＇相含量增加;并且使表面氮含量提高。     

Replacement of conventionally complex processing for low alloy steel 20Cr2Ni4A by rare earth carburising at lower temperature

Abstract

This paper deals with the effects of rare earth (RE) addition on the microstructure and properties of 20Cr2Ni4A steel carburised at 860°C. Compared with conventional 920°C carburising and other complex treatments, finer and more dispersed carbide precipitates formed in the surface layers. A superfine martensitic structure and a less residual austenite were obtained by direct quenching after RE 860°C carburising. The microstructure exhibited a higher microhardness, a wear resistant surface layer, and it also led to an increase in impact toughness. In addition, the heat treatment period for this steel was remarkably reduced by the replacement of conventional complex treatments by RE 860°C carburising.     

稀土元素在化学热处理中的催渗和扩散机理研究

稀土元素的特殊电子结构(4f)决定了它具有很高的化学活性,在化学热处理中能起到活化催渗作用,显著提高渗速;稀土元素被渗入钢件表层,有效地改善了渗层组织和性能.从化学热处理的基本过程入手,简要介绍了稀土在化学热处理中的作用,着重分析了稀土元素的活化催渗和扩散机理.     

20钢制纺织钢领C-N-RE共渗研究

为取代钢领生产厂家现行的碳氮共渗工艺,采用"无毒液体C-N-RE共渗"对20钢制纺织钢领进行了共渗试验,对共渗试样的显微组织、截面显微硬度、渗层碳浓度和稀土元素浓度进行了测定和研究。结果表明,经"无毒液体C-N-RE共渗"淬火后,20钢制纺织钢领的表面碳浓度大大增加,显微硬度大大提高,显微组织主要包含碳氮化合物、针状马氏体和残余奥氏体,稀土元素起到了良好的催渗作用。     

Electrical Excitation of Long-Range Surface Plasmons in PC/OLED Structure with Two Metal Nanolayers

A current-driven source of long-range surface plasmons(LRSPs)on a duplex metal nanolayer is reported.Electrical excitation of LRSPs was experimentally observed in a planar structure,where an organic light-emitting film was sandwiched between two metal nanolayers that served as electrodes.To achieve the LRSP propagation in these metal nanolayers at the interface with air,the light-emitting structure was bordered by a one-dimensional photonic crystal(PC)on the other side.The dispersion of the light emitted by such a hybrid PC/organic-light-emitting-diode structure(PC/OLED)comprising two thin metal electrodes was obtained,with a clearly identified LRSP resonance peak.     

稀土元素对钢渗碳过程的催化作用

本文研究了稀土元素对钢渗碳过程的影响．试验结果表明．无论采用固体法或气体法，稀土元素对钢的渗碳过程都有明显的催化作用，渗速提高２０－３０％．电子探针测定证实稀土元素Ｌａ、Ｙ和Ｃｅ等被渗入钢的表面．本文还讨论了稀土对渗碳的催渗过程与机理．